Necropsy tests are planned to determine why the first set of quadruplet fawns ever documented in North Dakota and the doe that carried them died.

The unprecedented birth was discovered in late May as part of a study the state Game and Fish Department is conducting in northeast North Dakota to track deer movement and mortality. Besides fitting 40 whitetail does with VHF collars, researchers in February inserted vaginal implant transmitters — VITs, for short — in 20 of the does to monitor fawn survival.

About the size of a tampon, the VITs eject when a fawn is born. The resulting drop in temperature changes the frequency of the VITs, allowing researchers to track down the newborn fawns and fit them with radio-collars.

Kristin Sternhagen, a South Dakota State University graduate student who’s tracking the deer, discovered the quadruplet fawns May 29 when she followed the VIT signal to a site southwest of Minto, N.D.

Within two days, two of the fawns had died, Sternhagen said. Within three days, the doe and a third fawn had died. The fourth fawn died two days after that.

“It was kind of inevitable,” she said.

Sternhagen said the initial discovery of the doe with quadruplets was “extremely exciting” because it had never been documented in North Dakota.

Bill Jensen, big game biologist for Game and Fish in Bismarck, said the odds of a doe having triplets is less than 2 percent. Scouring the literature, Jensen said he could find only six cases dating back to 1849 of white-tailed deer having quadruplets — anywhere in the country.

Tuesday, Sternhagen brought the doe and four fawns to Devils Lake, where Game and Fish staff were going to transport the deer to Bismarck for tests to determine why they all died.

Sternhagen said results should be available in a week or two.

According to Sternhagen, the doe and fawns appeared to be fine when she first encountered them. The doe was old, she said, but otherwise in good health; the fawns varied in size.

“There was one fairly big one, two about the same size and one fairly small one I didn’t think was going to make it, which ended up being one of the first ones to die,” she said.

Sternhagen said the smallest fawn was found at the bed site, while the rest were next to the Forest River nearby. There were no signs of predators.

As of Friday, Sternhagen said they had 11 fawns “on the air,” mostly singles except for two sets of twins; nine does hadn’t dropped their fawns.

Helping Sternhagen track the deer is Adam McDaniel, a UND student. The study area covers 500 square miles in Walsh and parts of Grand Forks counties, so keeping tabs on the animals means long days and lots of driving.

They try to check on each of the radio-collared does every day. But with fawning in progress, work has focused on tracking the VITs to find the offspring.

“We’ve been walking in on fawns and marking their bed sites so we can go back in and do habitat work and see what kind of conditions they’re bedding in,” she said. “It’s very long hours.”

The study, which began in January, will continue for two years, Sternhagen said.